Triplet-triplet energy transfer. and the overlap of singlet-triplet bands of sensitizer and acceptor. Remarks on the 'phantom triplet' of stilbene

Data on the rate of triplet-triplet energy transfer to stilbenes are reinterpreted in terms of the overlap of the T-1-S-o transition bands in the sensitizer and acceptor. So-called ''non-vertical" excitation follows closely the Franck-Condon probabilities in the spectra, the "phantom triplet" being identical with the spectroscopical triplet of stilbene.